JP3294087B2 - Fuel injection amount control device for internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection amount control device for an internal combustion engine, and more specifically to an adaptive controller and an adaptive control parameter for adjusting and estimating an adaptive control parameter (vector) input to the adaptive controller. In a fuel injection amount control device for a multi-cylinder internal combustion engine equipped with an adjusting mechanism, the load on a matrix operation for calculating an adaptive control parameter by synchronizing an input to an adaptive control parameter adjusting mechanism with a combustion cycle of a specific cylinder is reduced. In addition, the present invention relates to a system in which an input to an adaptive control parameter adjusting mechanism is synchronized with a combustion cycle so as not to be strongly affected by an exhaust gas air-fuel ratio of a specific cylinder.

[0002]

2. Description of the Related Art Recently, a modern control theory has been introduced also for an internal combustion engine, and a technique has been proposed in which an optimal regulator controls an amount of fuel actually taken into a cylinder so as to match a target fuel amount. JP-A 1-111085
No. 3 technology can be mentioned. Also, the present applicant has previously proposed a fuel injection amount control for an internal combustion engine using adaptive control, which is one of modern control theories, in Japanese Patent Application Laid-Open No. 6-161511.

[0003]

The adaptive control technique proposed by the present applicant will be described. The adaptive control technique comprises an adaptive controller composed of a STR (self-tuning regulator) controller and adjusts (or estimates) its adaptive control parameters.
The STR controller inputs a target value and a control amount (plant output) of the feedback system of the fuel injection amount control, and receives the adaptive control parameter (coefficient vector) identified by the adaptive control parameter adjusting mechanism. ) Receive the θ hat and calculate the output.

In such adaptive control, one of the adjustment rules is a parameter adjustment rule proposed by Landau et al. This method converts the adaptive control system into an equivalent feedback system consisting of linear and nonlinear blocks, and adjusts the nonlinear blocks so that Popov's integral inequality for input and output is satisfied and the linear blocks are strongly positive. This is a method that guarantees the stability of an adaptive control system by determining a rule.

That is, the adaptive control system has a problem of stability. In Landau et al.'S proposed parameter adjustment rule, the adjustment rule (adaptive rule) expressed in the form of a recurrence formula is evaluated by using at least one of the above-mentioned Popov's hyperstability theory or Lyapunov's direct method. Guaranteed.

[0006] This method is described in, for example, “Computer Roll” (Corona) No. 27, 28-41, or "Automatic Control Handbook" (Ohm), pages 703-707, "A Survey of Model Reference Adaptive
Techniques-Theory and Ap-plication "ID LANDAU
"Automatic" Vol. 10, pp. 353-379, "Unificationof
Discrete Time Explicit Model Reference Adaptive C
ontrol Designs "IDLANDAU and others" Automatic "Vol.
1, No. 4, pp. 593-611, and "CombiningModel Refe
rence Adaptive Controllers and Stochastic Self-tun
ing Regula-tors "ID LANDAU" Automatic "Vol. 1
8, No. 1, pp. 77-84.

The adaptive control technique proposed above uses the adjustment law of Landau et al. In the following, according to Landau et al.'S adjustment rule, when the polynomial of the denominator and numerator of the control target B / A in the discrete system is represented by Equation 1, the adaptive control parameter (vector) θ hat (k) and the adaptive control parameter adjustment The input ζ (k) to the mechanism is defined as in Equation 1. Here, in Equation 1, a case where m = 1, n = 1, and d = 3, that is, a plant having a dead time of three control cycles in the primary system is taken as an example.

[0008]

(Equation 1)

Here, the adaptive control parameter θ hat (k)
Is represented by Equation 2. Further, Γ (k) and e asterisk (k) in Equation 2 are a gain matrix and an identification error signal, respectively, and are represented by recurrence equations such as Equations 3 and 4.

[0010]

(Equation 2)

[0011]

(Equation 3)

[0012]

(Equation 4)

Various specific algorithms are given depending on how λ1 (k) and λ2 (k) in Equation 3 are selected. For example, when λ1 (k) = 1 and λ2 (k) = 0, the fixed gain algorithm is used, λ1 (k) = 1 and λ2 (k) = λ (0 <λ <
2), a gradually decreasing gain algorithm (least squares method when λ = 1), λ1 (k) = λ1 (0 <λ1 <1), λ
If 2 (k) = λ2 (0 <λ2 <λ), a variable gain algorithm (weighted least squares method in the case of λ2 = 1),
When λ1 (k) / λ2 (k) = σ and λ3 is expressed as in Equation 5, setting λ1 (k) = λ3 results in a fixed trace algorithm.

[0014]

(Equation 5)

By the way, when controlling the fuel injection amount of the internal combustion engine, as shown in FIG. 17, the injection amount is calculated, and a certain time is required until the calculated fuel is compressed, exploded and exhausted in the cylinder. It costs. Furthermore, considering the time required for the exhaust gas to reach the air-fuel ratio sensor, the detection delay of the sensor itself, and the time required to calculate the amount of fuel actually sucked into the cylinder from the detected value, this time is further reduced. growing.
As described above, dead time is inevitably involved in controlling the fuel injection amount of the internal combustion engine. Assuming that the dead time is, for example, three times in the combustion cycle as described above by focusing on one cylinder, the TDC number is 12 TDC when the internal combustion engine is four cylinders.

In the above-described adaptive controller (STR controller), the number of elements of the adaptive control parameter θ hat (k) is proportional to the dead time d, as is apparent from Equation 1. As in the previous example, when the dead time is 3, when the STR controller and the adaptive control parameter adjustment mechanism are operated in TDC synchronization in order to cope with the ever-changing operation state, the element of the adaptive control parameter θ hat (k) Is m
= N = 1, as shown in FIG. 18, d = 12
(3 combustion cycles × 4 TDC), and 12 + 1 (scalar amount for determining gain) +1 (number of elements using plant output) = 14. As a result, the operation such as the gain matrix と な り becomes a 14 × 14 matrix operation, the amount of operation increases, and the load on the on-vehicle computer increases.
It will be difficult to complete the calculation within.

Although a normal fuel control cycle is performed for each TDC, about 8 to 12 TDCs are required from the injection of fuel to the detection of a control result, so that there is a dead time of 8 to 12 control cycles. . When the dead time of the control target is long, the controllability generally deteriorates as compared with the case where the dead time is short. This is particularly noticeable in adaptive control.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve the above-mentioned inconveniences, to cope with ever-changing operating conditions as much as possible, and to reduce the amount of matrix calculations to reduce the load on the on-board computer. It is an object of the present invention to provide a combustion injection amount control device for an internal combustion engine by adaptive control in a real machine while ensuring controllability.

Furthermore, if the input to the adaptive control parameter adjusting mechanism is performed in synchronization with the combustion cycle as described later, for example, d = 3, and the number of elements of the adaptive control parameter θ hat (k) becomes 5, the calculation such as the gain matrix Γ is reduced to a 5 × 5 matrix calculation, and the load on the on-vehicle computer is reduced, and the calculation can be performed within 1 TDC. Further, by reducing the dead time, controllability can be improved.

On the other hand, when the input to the adaptive control parameter adjusting mechanism is performed in synchronization with the combustion cycle, the input is performed in synchronization with the predetermined crank angle of the specific cylinder. Will be strongly received. As a result, when controlling the stoichiometric air-fuel ratio, for example, when the exhaust gas air-fuel ratio of the specific cylinder is in the lean direction and that of the remaining cylinders is in the rich direction, the adaptive controller adjusts the operation amount in the rich direction. As a result, the air-fuel ratio of the remaining cylinders may be further increased in the rich tendency.

Accordingly, a second object of the present invention is to eliminate the above-mentioned disadvantages, and to reduce the number of elements of the adaptive control parameter by inputting the adaptive control parameter adjusting mechanism in synchronization with the combustion cycle. It is another object of the present invention to provide a fuel injection amount control device for an internal combustion engine which is not strongly affected by the exhaust gas air-fuel ratio of a specific cylinder even when the amount of matrix calculation is reduced.

[0022]

In order to achieve the above object, according to the present invention, there is provided a fuel injection amount control means for controlling a fuel injection amount of a multi-cylinder internal combustion engine; an adaptive controller for adaptively matched with the target value, the adaptive
The fuel injection amount control apparatus for a multi-cylinder internal combustion engine having an adaptive control parameter adjusting mechanism for adjusting the adaptive control parameters of the controller, synchronizing the fuel injection amount control means to the fuel control cycle for each predetermined crank angle of each cylinder The adaptive control parameter is adjusted by considering the dead time of the control target of the adaptive controller as a value synchronized with a combustion cycle obtained by multiplying the fuel control cycle by n (n: an integer of 2 or more). An input to the mechanism is performed in synchronization with the combustion cycle, and based on the input, the
Response parameter adjusting mechanism is constructed as you adjust the adaptive parameters.

According to a second aspect of the present invention, the input to the adaptive control parameter adjusting mechanism is performed by obtaining an average value of a control amount for each of the fuel control cycle or the combustion cycle and performing the adaptive control. The parameter adjustment mechanism is configured to adjust the adaptive control parameter based on the average value.

According to a third aspect of the present invention, the input to the adaptive control parameter adjusting mechanism is performed by obtaining an average value of the adaptive control parameters for each of the fuel control cycle or the combustion cycle, and The control parameter adjusting mechanism is configured to adjust the adaptive control parameter based on the average value.

According to a fourth aspect of the present invention, the target value is at least one of a fuel injection amount, an equivalent ratio, and an air-fuel ratio.

[0026]

[Action] In the Claim 1, wherein, the fuel injection amount control means together operating in synchronism with the fuel control cycle for each predetermined crank angle of each cylinder, wherein the dead time of the controlled object adaptive controller fuel Control cycle is multiplied by n (n: 2 or more
Number) is regarded as a value synchronized with the combustion cycle
An input for proper応制control parameter adjusting mechanism to perform in synchronization with said combustion <br/> cycle, on the basis of the said input
Since the adaptive parameter adjustment mechanism is configured to adjust the adaptive parameter, the amount of matrix operation can be reduced and the load on the on-board computer can be reduced. it can. Further, the controllability can be improved by reducing the dead time.

[0027] Here, (the period In the four-cylinder internal combustion engine corresponding to 4TDC minutes) and long periodic than a predetermined crank angle of each cylinder (e.g. TDC position), is inherently one combustion cycle However, the present invention is not limited to this, and may be 2 to 3 TDC or the like having less than one combustion cycle. Alternatively, as the combustion cycle, depending on the performance of a vehicle-mounted computer or the like, 8 TDC (two combustion cycles) or 12 TDC larger than one combustion cycle.
(3 combustion cycles).

As described above, by synchronizing the input to the adaptive control parameter adjusting mechanism with a cycle longer than the control cycle of the fuel injection amount control means, the load on the on-board computer is reduced, and the control accuracy is reduced due to an increase in the dead time. By adjusting the adaptive control parameters once in the combustion cycle or once in a cycle less than that, it is possible to respond to changes in the operating state as much as possible.
Note that the combustion cycle may be the same as that in which the parameter adjustment mechanism operates in synchronization, or may be longer than that.

According to a second aspect of the present invention, the input to the adaptive control parameter adjusting mechanism is performed by obtaining an average value of a control amount for each of the fuel control cycle or the combustion cycle and performing the adaptive control. Since the parameter adjustment mechanism is configured to adjust the adaptive control parameter based on the average value, even if the input to the adaptive control parameter adjustment mechanism is performed in a cycle longer than the predetermined crank angle, for example, in synchronization with a combustion cycle, There is no strong influence of the exhaust gas air-fuel ratio of the specific cylinder. Here, the average value may be any of a simple average, a weighted average, a moving weighted average, and the like.

According to a third aspect of the present invention, the input to the adaptive control parameter adjusting mechanism is performed by obtaining an average value of the adaptive control parameters for each of the fuel control cycle or the combustion cycle, and Since the control parameter adjusting mechanism is configured to adjust the adaptive control parameter based on the average value, the same operation as in claim 2,
Has an effect.

According to a fourth aspect of the present invention, the target value is at least one of a fuel injection amount, an equivalence ratio, and an air-fuel ratio, so that the actual fuel injection amount is adapted to match the target fuel injection amount. Even when the controller and the adaptive control parameter adjustment mechanism operate, the amount of calculation can be reduced and the change in the operating state can be coped with as much as possible, as described in claim 1. It is not affected by a specific cylinder.

[0032]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 shows a fuel injection amount control device for an internal combustion engine according to the present invention. In the figure, reference numeral 10 denotes a four-cylinder internal combustion engine, and intake air introduced from an air cleaner 14 disposed at the tip of an intake passage 12 is supplied to a throttle valve 1.
At 6, the gas flows into the first to fourth cylinders via the surge tank 18 and the intake manifold 20 while the flow rate is adjusted. An injector 22 is provided near an intake valve (not shown) of each cylinder to inject fuel. The air-fuel mixture that has been injected and integrated with the intake air is ignited by an ignition plug (not shown) in each cylinder and burns to drive a piston (not shown). The exhaust gas after combustion is discharged to an exhaust manifold 24 via an exhaust valve (not shown), purified through an exhaust pipe 26 by a three-way catalytic converter 28, and discharged outside the engine.

In a distributor (not shown) of the internal combustion engine 10, a crank angle sensor 34 for detecting a crank angle position of a piston (not shown) is provided.
A throttle opening sensor 36 for detecting the opening of the throttle valve 16 and an intake pressure sensor 38 for detecting the intake pressure Pb downstream of the throttle valve 16 as an absolute pressure are also provided. An air pressure sensor 40 for detecting the air pressure Pa and an intake air temperature sensor 42 for detecting the temperature of the intake air are provided upstream of the throttle valve 16.
Is provided, and a water temperature sensor 44 for detecting an engine cooling water temperature is provided at an appropriate position of the engine.

Further, in the exhaust system, a wide-range air-fuel ratio sensor 46 is provided on the downstream side of the exhaust manifold 24 and on the upstream side of the three-way catalytic converter 28, and detects the air-fuel ratio of the exhaust gas in the exhaust system collecting part. Outputs of these sensors 34 and the like are sent to the control unit 50.

FIG. 2 is a block diagram showing details of the control unit 50. The output of the wide-range air-fuel ratio sensor 46 is input to the detection circuit 52, where appropriate linearization processing is performed, and the air-fuel ratio (A) having a linear characteristic proportional to the oxygen concentration in the exhaust gas in a wide range from lean to rich. /
F) is detected. The details are described in an application proposed by the present applicant (Japanese Patent Application Laid-Open No. 4-369471, pages 3 et seq.), And further description is omitted (hereinafter simply referred to as "air-fuel ratio sensor"). . The output of the detection circuit 52 is A /
CPU 56, ROM 58, RA via D conversion circuit 54
It is taken into the microcomputer composed of M60 and stored in RAM60.

Similarly, an analog output from the throttle opening sensor 36 and the like is supplied to a level conversion circuit 62 and a multiplexer 64.
After the output of the crank angle sensor 34 is shaped by a waveform shaping circuit 68 via a second A / D conversion circuit 66, the output value is counted by a counter 70, and the count value is stored in a microcomputer. Is entered. In the microcomputer, the CPU 56 calculates the control value in accordance with the command stored in the ROM 58 as described above, and drives the injector 22 of each cylinder via the drive circuit 72.

FIG. 3 is a flow chart showing the operation of the control device according to the present invention, and FIG. 4 is a block diagram showing the operation more functionally. For convenience of understanding, the apparatus according to the present invention will be described with reference to FIG. 4 first. In the case of the illustrated example, the STR controller (adaptive controller) and the adaptive control parameter adjustment mechanism are connected to a fuel injection amount calculation system. Outside, the detected air-fuel ratio KACT (k) becomes the target air-fuel ratio KCMD.
(k) is adaptively operated to calculate a feedback correction term KSTR (k). The calculated feedback correction term is multiplied by the fuel injection amount, and the corrected injection amount is supplied to the control plant (internal combustion engine).

In this embodiment and the following embodiments, the target air-fuel ratio and the detected air-fuel ratio are actually represented by equivalent ratios in consideration of the convenience of the calculation for correcting the injection amount. Needless to say, the equivalent ratio is a value represented by Mst / M = 1 / λ (Mst: stoichiometric air-fuel ratio, M = A / F (A: air consumption, F: fuel consumption), λ = air excess ratio ).

In FIG. 4, more specifically, the basic injection amount Tim is calculated in a feedforward system. This calculation is performed by retrieving, from the engine speed Ne and the engine load Pb, characteristics obtained in advance through experiments and mapped. The target air-fuel ratio correction term KC is added to the calculated basic injection amount Tim.
MDM (determined by performing charging efficiency correction with appropriate characteristics to the target air-fuel ratio because the charging efficiency of the intake air amount differs due to heat of vaporization) and other correction terms KTOTAL (various correction terms performed by multiplication terms such as water temperature correction) Is multiplied to determine the injection amount Tcyl (k) required by the internal combustion engine (control plant).

The output (control amount) of the internal combustion engine (control plant) is detected through the above-described air-fuel ratio sensor 46, and the air-fuel ratio KACT (k) is obtained from the detected value and input to the adaptive control parameter adjusting mechanism, where it is adapted. The control parameter θ hat (k) is calculated and input to the STR controller. The target air-fuel ratio K is input to the STR controller as an input.
CMD (k) is given, and the feedback correction term KSTR (k) is calculated using the recurrence formula so that the detected air-fuel ratio KACT (k) matches the target air-fuel ratio KCMD (k). That is, the STR controller receives the coefficient vector θ hat (k) identified by the adaptive control parameter adjustment mechanism and forms a feedback compensator.

The calculated feedback correction term KSTR
(k) is multiplied by the required injection amount Tcyl (k) to determine the output injection amount Tout (k) and the determined injection amount Tcyl (k).
Adhesion correction is performed by multiplying cyl (k) by an adhesion coefficient obtained by searching an adhesion coefficient map from the engine cooling water temperature and the like, and the correction value is supplied to the internal combustion engine (control plant). Note that the adhesion correction itself does not directly relate to the gist of the present invention, and thus the description thereof will be omitted.

The feedback correction coefficient KSTR (k) is
Specifically, it is obtained as shown in Expression 6.

[0044]

(Equation 6)

In the above description, the fuel injection amount control means shown in the upper part of FIG. 4 is operated in synchronization with a predetermined crank angle of each cylinder, for example, TDC, as will be described later with reference to the flowchart of FIG. As shown in FIG.
The STR controller is also operated in synchronization with a predetermined crank angle of each cylinder, for example, TDC. On the other hand, the input to the adaptive control parameter adjustment mechanism is performed in synchronization with a combustion cycle that is longer than the predetermined crank angle, and the adaptive control parameter adjustment mechanism is operated (calculated) in synchronization with the combustion cycle. I do.

Thus, the adaptive control parameter θ hat
Stop the number of elements of (k) to 5 and calculate the gain matrix Γ by 5 ×
5 matrix operations. Therefore, the load on the in-vehicle computer can be reduced, and the calculation can be completed in one TDC with the usual in-vehicle computer.
In addition, controllability is improved by reducing wasted time.

As described above, the input to the adaptive control parameter adjustment mechanism is operated in synchronization with the combustion cycle, that is, the adaptive control parameter adjustment mechanism is operated, that is, is operated in synchronization with the predetermined crank angle of the specific cylinder among the four cylinders. I did it. Then, as shown in FIG. 4, the control amount y (k) is changed to a predetermined crank angle of each cylinder during a combustion cycle, for example, TDC.
Each time, an average value of the detected air-fuel ratio KACT (k), for example, a simple average value is obtained and input to the adaptive control parameter adjustment mechanism.

Thus, the exhaust gas air-fuel ratio of the specific cylinder is not greatly affected. FIG. 5 is an explanatory view showing the configuration of FIG. 4 focusing on the adaptive controller and the parameter adjustment mechanism. As described above, the STR controller is synchronized with the TDC of each cylinder, and the parameter adjustment mechanism is operated in synchronization with the combustion cycle. The configuration to be performed is shown.

Based on the above, the operation of the control device according to the present invention will be described with reference to the flowchart of FIG.
The program in FIG. 3 is started at a predetermined crank angle of each cylinder, for example, at TDC.

First, the engine speed N detected in S10
e, the intake pressure Pb, and the like are read, and the process proceeds to S12 to determine whether or not cranking is performed. If the result is NO, the process proceeds to S14 to determine whether or not fuel cut is performed. The fuel cut is performed in a predetermined operating state, for example, when the throttle valve opening is at the fully closed position and the engine speed is equal to or higher than a predetermined value, the fuel supply is stopped, and the injection amount is controlled in an open loop. You.

If it is determined in S14 that the fuel cut is not performed, the program proceeds to S16, in which a map is retrieved from the detected engine speed Ne and intake pressure Pb to calculate the basic fuel injection amount Tim described above.

Next, the program proceeds to S18, in which it is determined whether the activation of the air-fuel ratio sensor 46 has been completed. This is performed, for example, by comparing the difference between the output voltage of the air-fuel ratio sensor 46 and its center voltage with a predetermined value (for example, 0.4 V), and determining that activation has been completed when the difference is smaller than the predetermined value. If it is determined that the activation has been completed, the process proceeds to S20, and it is determined whether or not the activation is in the feedback control region. When the operating state suddenly changes due to fuel cut, full opening increase, or EGR control, the injection amount is controlled in an open loop.

When it is determined in step S20 that the engine is in the feedback control range, the process proceeds to step S22, and the detected exhaust gas air-fuel ratio (A
/ F), and proceeds to S24 to determine a detected air-fuel ratio KACT (k) from the detected exhaust gas air-fuel ratio. Then S2
Proceeding to 6, the feedback correction term KSTR (k) is obtained.

FIG. 6 is a subroutine flowchart showing the operation.

Referring to the figure, in S50, it is determined whether or not it is time to calculate the adaptive control parameter θ hat (k). As described above, in the illustrated configuration, the combustion cycle is synchronized, that is, for example, the combustion order is changed to the first, third, and third combustion cycles.
When the fourth and second cylinders are used, for example, the predetermined crank angle (for example, TDC) of the first cylinder is set to the operation timing of the adaptive control parameter adjustment mechanism, that is, the adaptive control parameter θ hat (k).
Calculation timing.

If the result in S50 is affirmative, the program proceeds to S52, in which the presently calculated air-fuel ratio KACT (k) calculated for the first cylinder in S24 of FIG. 3 and the previously calculated air-fuel ratio KACT (k-1) for the second cylinder. ), The average value KACTAVE of the previous and previous calculated air-fuel ratio KACT (k-2) for the fourth cylinder and the average value KACTAVE of the previous and previous calculated air-fuel ratio KACT (k-3) for the third cylinder is obtained, and the plant output (control amount) y (k)). That is, the program loop number (control cycle) in FIG. 3 is traced back three times, and a simple average value of the air-fuel ratio calculated during one combustion cycle for the four cylinders including the cylinder is obtained, and the control amount y (k) is obtained. And

Then, the process proceeds to S54, where the adaptive control parameter adjusting mechanism determines the control amount y just obtained, as shown at the end of FIG.
Using (k) and the past value of the output u of the STR controller synchronized with the combustion cycle as input, the adaptive control parameter θ hat (k) is calculated according to Equation 1 and input to the STR controller. Then, the process proceeds to S56, where the STR controller calculates the feedback correction term KSTR (k) according to Equation 6 based on the input value.

As described above, since the average value of the air-fuel ratios of all the cylinders is obtained and input as the control amount y (k), the air-fuel ratio of the specific cylinder (for example, the first cylinder), more specifically, the exhaust gas It is not greatly affected by the air-fuel ratio. Further, as for the STR controller output, a signal vector ζ is obtained by using values of four control cycles including the latest value u (k) and input to the adaptive control parameter adjustment mechanism, so that the exhaust gas air-fuel ratio of the specific cylinder is obtained. Is further reduced.

In step S50, the adaptive control parameter θ hat
If it is not the calculation timing of (k), that is, if it is other than the predetermined crank angle of the first cylinder, the process proceeds to S56, and the feedback correction term KSTR is calculated based on the adaptive control parameter θ hat calculated in S54 in the previous program loop.
(k) is calculated.

Returning to the flow chart of FIG.
28, the required injection amount Tcyl (k) is obtained, and S3
The process proceeds to 0 to obtain the output injection amount Tout (k), and proceeds to S32 for output. It should be noted that TTOTAL in S30 indicates the total value of various correction coefficients performed in an addition term such as air pressure correction (however, the invalid time of the injector is not included since it is separately added when the output injection amount Tout is output). ).

If the result in S18 or S20 is negative, the program proceeds to S34, in which the feedback correction term is fixed at 1.0 (feedback correction is stopped), and the program proceeds to S28 and thereafter. If it is determined in step S12 that cranking is to be performed, the process proceeds to step S36, in which a fuel injection amount Ticr at the time of cranking is searched.
38, the output injection amount Tout is calculated according to the equation of the start mode.
Is calculated, and when it is determined in S14 that the fuel is cut, the process proceeds to S40, where the output injection amount Tout is set to zero.

As a result of the above configuration, as shown in FIGS. 5 and 7, the adaptive control parameter adjusting mechanism operates only once every combustion cycle (corresponding to 4 TDC), and the adaptive control parameter element When the number is 5,
The matrix operation is reduced to 5 × 5, so that the load on the in-vehicle computer is reduced, and the in-vehicle computer with ordinary performance can complete the operation in 1 TDC. In addition, the controllability is improved by reducing the dead time. On the other hand, the STR controller calculates the feedback correction term KSTR for each TDC, and changes the adaptive control parameter θ hat used for the calculation once per combustion cycle, so that the STR controller can respond to changes in the operating state as much as possible. it can.

Further, the input to the adaptive control parameter adjusting mechanism is a combustion cycle, and the adaptive control parameter adjusting mechanism operates in synchronization with the combustion cycle. As a result, the adaptive control parameter adjusting mechanism operates at a predetermined crank angle of a specific cylinder, for example, the first cylinder. , The average value of the detected air-fuel ratios (control amounts) for all the cylinder groups including the remaining cylinders during the combustion cycle is determined, and the average value is input to the adaptive control parameter adjustment mechanism. Therefore, there is no inconvenience that strongly reflects only the combustion state of the specific cylinder.

That is, when the adaptive control parameter θ hat (k) is obtained based on the control amount for the specific cylinder, for example, when the air-fuel ratio of the first cylinder is rich and that of the other cylinder is lean, the feedback correction coefficient The KSTR is determined so as to correct the air-fuel ratio in the lean direction, which spurs the leaning of the air-fuel ratio of the other cylinders. However, such an inconvenience does not occur as a result of the average value of all the cylinders.

Next, an apparatus according to a second embodiment of the present invention will be described with reference to a flow chart of FIG. 8 and a timing chart of FIG.

In the apparatus according to the second embodiment, as shown in FIG. 9, the STR controller is also operated in synchronization with the combustion cycle. As a result, as compared with the first embodiment, the feedback correction term K of S26 in FIG.
Only the STR operation part is different.

Referring to the flow chart of FIG. 8, it is determined in S100 whether or not it is time to calculate the feedback correction term KSTR. In the second embodiment, the operation timing of the STR controller, that is, the calculation timing of the feedback correction term KSTR, is set to once a combustion cycle, for example, a predetermined crank angle of the first cylinder (for example, TDC).

If the result in S100 is affirmative, S10
2 and the current calculated air-fuel ratio KAC calculated for the first cylinder in the same manner as in the process of S52 in the flow chart of FIG.
T (k), the previously calculated air-fuel ratio KACT (k
-1), the air-fuel ratio KACT (k
-2), the previous and previous calculated air-fuel ratio KACT for the third cylinder
The average value KACTAVE of (k-3) is obtained and set as the plant output (control amount y (k)).

Then, the process proceeds to S104, in which the control amount y (k) just obtained by the adaptive control parameter adjusting mechanism and the past value of the output u (k) of the STR controller synchronized with the combustion cycle are input as follows. The adaptive control parameter θ hat (k) is calculated according to the following formula, and is input to the STR controller. Then, the process proceeds to S106, where the STR controller similarly calculates the feedback correction term KSTR (k) according to Equation 6 based on the input value.

As described above, in the apparatus according to the second embodiment, similarly to the first embodiment, the average value of the air-fuel ratios of all the cylinders is obtained, and the control amount y (k ) Is not greatly affected by the air-fuel ratio of the specific cylinder (for example, the first cylinder), and the STR controller output uses the value for the four control cycles including the latest value u (k). Since the signal vector ζ is obtained and input to the adaptive control parameter adjusting mechanism, the influence of the exhaust gas air-fuel ratio of the specific cylinder can be further reduced.

In S100, the feedback correction term KS is set.
If it is not the calculation timing of TR, that is, if it is at the predetermined crank angle of a cylinder other than the first cylinder, the process proceeds to S108,
The feedback correction term is the previous value (the value at the time of the previous loop in FIG. 3) KSTR (k-1).

As a result of the above configuration, in the second embodiment, as shown in FIG. 9, the adaptive control parameter adjusting mechanism operates only once for each combustion cycle, and the number of elements of the adaptive control parameter Becomes 5 and the Γ matrix operation is reduced to 5 × 5, so that the load on the in-vehicle computer is reduced, and the operation can be completed in 1 TDC with the in-vehicle computer having ordinary performance. In addition, the controllability is improved by reducing the dead time. On the other hand, the STR controller also calculates the feedback correction term KSTR for each combustion cycle, and changes the feedback correction term KSTR once in the combustion cycle to further reduce the load on the on-vehicle computer and respond to changes in the operating state to some extent. be able to.

FIG. 10 shows an apparatus according to a third embodiment of the present invention. FIG. 11 is a block diagram similar to FIG. 4, FIG. 11 shows the operation thereof, FIG. 12 is a flow chart similar to FIG. 10 is a timing chart similar to FIG. 9.

In the device according to the third embodiment,
As shown in FIG. 12, only the input to the adaptive control parameter adjustment mechanism is synchronized with the combustion cycle,
The operation of the controller and the adaptive control parameter adjustment mechanism
This is performed in synchronization with a predetermined crank angle of each cylinder, for example, TDC. That is, based on the configuration shown in FIG. 5, the STR controller is operated in synchronization with the predetermined crank angle (TDC) of each cylinder, and the adaptive control parameter adjustment mechanism is operated in synchronization with the same crank angle. Only the input to is operated in synchronization with the combustion cycle.

Therefore, in the apparatus according to the third embodiment, as shown in FIG. 10, the adaptive control parameter θ hat (k) on the output side of the adaptive control parameter adjustment mechanism is not the input side, but the four cylinders. Θ (k), θ (k-1), θ for four control cycles (one combustion cycle) corresponding to
The average value of the hat (k-2) and the θ hat (k-3), for example, a simple average value AVE-θ hat (k) was obtained and input to the STR controller.

In this case, since the adaptive control parameter θ hat (k) is a vector, as shown in Equation 1, the average value is obtained by averaging each element of the vector.
What is necessary is just to obtain E-θ hat (k). Further, one element of the adaptive control parameter θ hat (k), for example, b
It is also conceivable to take the average value of 0 and average the other elements at the same ratio as b0. FIG. 10 and FIG. 11 schematically show these methods.

Referring to the flow chart of FIG. 11, it is determined in S200 whether or not it is time to calculate the feedback correction term KSTR. If the determination is affirmative, the process proceeds to S202, in which the detected air-fuel ratio KACT calculated in S24 of FIG. (k)
Is the control amount y (k), and y (k) and the controller output u
(k) and the signal vector ζ is obtained and input to the adaptive control parameter adjustment mechanism.

In this case, the feedback correction term KSTR
Is calculated at the TDC of each cylinder,
When the result is affirmative, the arithmetic operation of the adaptive control parameter adjusting mechanism and the operation of the STR controller are performed together. When the program of the flowchart shown in FIG. 3 is executed in synchronization with the TDC of each cylinder, the result in S200 is always affirmative.

In step S204, the parameter adjusting mechanism controls the control amount y (k) in the same manner as in the first and second embodiments.
And the output u of the STR controller synchronized with the combustion cycle
The adaptive control parameter θ hat (k) is calculated from input values such as the past value of (k), and the calculated values θ hat (k) or θ hat (k−3) up to three control cycles before that are included. An average value, for example, a simple average value AVE-θ hat (k) is calculated.

Then, in S206, the STR controller calculates the feedback correction term KSTR based on the average value AVE-θ hat (k). When the result in S200 is negative, the process proceeds to S208 and the feedback correction term is set to the previous value, which is not different from the case of the second embodiment.

In the apparatus according to the third embodiment,
Even if the adaptive control parameter adjustment mechanism calculates the adaptive control parameter θ hat (k) for each TDC while synchronizing the input of the adaptive control parameter adjustment mechanism with the combustion cycle, ST
Since the R controller calculates the feedback correction term from the average value reflecting the control amounts of all cylinders, the feedback correction term is not greatly affected by the specific cylinder.

Further, in the device according to the third embodiment, the adaptive control parameter adjusting mechanism performs the calculation of the adaptive control parameter based on the input made in synchronization with the combustion cycle.
Since the operation is performed for each DC, the number of elements of the adaptive control parameter becomes 5, the Γ matrix operation is reduced to 5 × 5, and the load on the onboard computer is reduced. As a result, it becomes possible for a vehicle-mounted computer with ordinary performance to complete the calculation in one TDC.

On the other hand, the STR controller calculates the feedback correction term KSTR for each TDC, and also changes the adaptive control parameter θ hat (k) used for the calculation for each TDC, so that the calculation amount is reduced as much as possible. It is possible to respond to a change in the operating state with high responsiveness.

Incidentally, the first or second embodiment is combined with the third embodiment, and an average value is obtained for both the detected air-fuel ratio KACT and the adaptive parameter θ hat (k). Needless to say, it can be done.

FIGS. 13 and 14 are a flow chart and a block diagram showing the operation of the apparatus according to the fourth embodiment of the present invention.

Referring to FIG. 14 first, in the case of the fourth embodiment, a cylinder-by-cylinder feedback loop based on the PID control law is inserted in the configuration of the second embodiment. That is, from the output of a single air-fuel ratio sensor disposed in the exhaust system collecting section, the air-fuel ratio #nA of each cylinder is obtained by using the observer previously proposed by the present applicant in Japanese Patent Application Laid-Open No. 5-180040.
/ F is estimated, a feedback correction term #nKLAF for each cylinder is obtained by using a PID control law in accordance with a deviation between the estimated value and a predetermined target value of the cylinder-by-cylinder air-fuel ratio feedback system, and the output injection amount #nTout is calculated. The multiplication correction is performed (n: cylinder).

More specifically, the feedback correction term #nKLAF for each cylinder is a value obtained by dividing the collective air-fuel ratio by the previously calculated value of the average value of the feedback correction term #nKLAF for each cylinder (this is the above-mentioned value). The target value of the air-fuel ratio feedback system for each cylinder is thus different from the target air-fuel ratio KCMD, and the PID is set so as to eliminate the deviation between the target air-fuel ratio KCMD and the estimated air-fuel ratio # nA / F. Determined using control rules. The details are described in Japanese Patent Application No. 5-251138 separately proposed by the present applicant, and therefore, the description thereof is omitted. The illustration of the adhesion correction compensator is omitted.

FIG. 1 shows the operation of the apparatus according to the fourth embodiment.
Referring to the 3 main flow chart, the process proceeds to S312 via steps S300 to S310 similar to those in the first embodiment, and it is determined in S312 whether or not it is the KSTR calculation timing. The KSTR calculation timing is, for example, a predetermined crank angle (TDC) of the first cylinder, as in the case of the second embodiment.

If the result in S312 is affirmative, S31
Proceeding to S4, the average value KACTAVE of the air-fuel ratio during one combustion cycle is calculated for all cylinders, and proceeding to S316 to calculate the feedback correction term KSTR (k).

Subsequently, the program proceeds to S318 and S320 to obtain the required injection amount Tcyl (k) and the output injection quantity Tout, and proceeds to S322 to set the air-fuel ratio #n of each cylinder via the above-mentioned observer.
A / F is estimated, and the process proceeds to S324 to calculate a feedback correction term #nKLAF for each cylinder. The process proceeds to S326 to calculate a learning value #nKLAFst from a weighted average value with the previous value.
y is determined, the flow proceeds to S328, and the output injection amount Tout is multiplied and corrected by the feedback correction term #nKLAF for each cylinder to obtain the output injection amount #nTout of the cylinder, and the flow proceeds to S330 to output.

If the result in S312 is NO, S331
, The feedback correction term KSTR is kept at the previous value, and when the result in S308 or S310 is negative, the program proceeds to S332 to obtain the required injection amount Tcyl (k) as shown in the figure, and the program proceeds to S334 to provide feedback for each cylinder. The learning value of the correction term #nKLAFsty is read, and the flow advances to S336 to set the learning value as the correction term #nKLAFsty.

If it is determined in step S304 that the fuel-cut operation has been performed, the flow advances to step S346 via step S342 to stop the observer matrix calculation, and the flow advances to step S348 to set the feedback correction term for each cylinder to the previous value. The remaining steps are not different from the first embodiment.

Also in the fourth embodiment, since the average value of the air-fuel ratio KACT during one combustion cycle is obtained and input to the parameter adjusting mechanism, the influence of the combustion state of the specific cylinder is not greatly affected.

When the first or third embodiment is combined with a cylinder-by-cylinder feedback loop based on the PID control law, the steps from S312 to S316 are replaced by the flow chart of FIG. 6 or FIG. Should be applied.

Further, in the fourth embodiment, the third
It is needless to say that the average value of the adaptive control parameter θ hat may be obtained in the same manner as in the embodiment, or the average value of the air-fuel ratio KACT and the average value of the adaptive control parameter θ hat may be obtained. The target air-fuel ratio KCMD (k) is
The same value may be used for all cylinders.

FIGS. 15 and 16 are a flow chart and a block diagram showing the operation of the device according to the fifth embodiment of the present invention.

In the case of the device according to the fifth embodiment, FIG.
As shown in FIG. 6, the STR controller and the parameter adjustment mechanism were inserted in series in the fuel injection amount calculation system. That is, after multiplying the basic injection amount Tim by the target air-fuel ratio correction term KCMDM (k) and the various correction terms KTOTAL to obtain the output injection amount Tout (k), the PID control law is determined from the detected exhaust system air-fuel ratio. Then, the feedback correction term KLAF of the collecting part is obtained, and the output injection amount Tout (k) is multiplied and corrected to obtain the required injection amount Tcyl (k), and the required injection amount Tcyl (k) is input to the STR controller.

On the other hand, the average value KACTAVE of the air-fuel ratio is obtained from the detected air-fuel ratio of the exhaust system as in the first embodiment, and is multiplied by the required injection amount Tcyl (k). The fuel amount Gfuel (k) is obtained.

Here, the actual intake fuel amount Gfuel (k) can be obtained by dividing the detected air amount by the detected air-fuel ratio, but in the case of the embodiment, an air amount detector (air flow meter) Therefore, the target intake fuel amount (required injection amount) Tcyl (k) is multiplied by the detected air-fuel ratio. As a result, the actual intake fuel amount can be obtained in a manner equivalent to detecting and obtaining the air amount.

If the target air-fuel ratio is not the stoichiometric air-fuel ratio, the calculated value is further divided by the target air-fuel ratio to obtain the actual intake fuel amount. That is, when the target air-fuel ratio is the stoichiometric air-fuel ratio, the actual intake fuel amount is calculated as: actual intake fuel amount = required injection amount (target intake fuel amount) × detected air-fuel ratio, and when the target air-fuel ratio is other than the stoichiometric air-fuel ratio. Is determined by the following formula: actual intake fuel amount = (required injection amount (target intake fuel amount) × detected air-fuel ratio) / target air-fuel ratio.

In FIG. 16, the STR controller determines that the actual intake fuel amount Gfuel (k) is the target intake fuel amount (required injection amount).
The output fuel amount Tout-str (k) is calculated by estimating the wall adhesion amount so as to coincide with Tcyl (k), and is supplied to the internal combustion engine as the output injection amount Tout (k). The collective feedback correction term KLAF is determined by the detected air-fuel ratio and the output injection amount Tout.
PI based on the deviation from the target air-fuel ratio calculated from
It is calculated based on the D control law, and is multiplied by the output injection amount Tout (k). As described above, by performing correction in advance in accordance with the deviation from the target value, the controllability can be improved as a whole by reducing the amount of correction by the STR controller.

The above will be described with reference to the flowchart of FIG. 15. The process proceeds to S418 through steps S400 to S416 similar to those in the previous embodiment, and calculates an average value KACTAVE of the air-fuel ratio. The output injection amount is determined and output as described above. In the case of the fifth embodiment, the calculation of the average value of the air-fuel ratio is not limited to the predetermined crank angle of the first cylinder, but is performed at the predetermined crank angle of each cylinder, unlike the previous embodiment. The remaining configuration is not different from the previous embodiment.

Also in the fifth embodiment, since the average value of the control amounts of all the cylinders is obtained and input to the parameter adjustment mechanism, the influence of the combustion state of the specific cylinder is not greatly affected. Note that, similarly to the third embodiment, the average value of the adaptive control parameter θ hat (k) may be obtained, or both the air-fuel ratio and the average value of the adaptive control parameter may be obtained.

In the first to fifth embodiments, the simple average value is shown as the average value. However, the present invention is not limited to this, and may be a weighted average value, a moving average value, a weighted moving average value, or the like. . In addition, the average value during one combustion cycle in which the adaptive control parameter adjustment mechanism operates in synchronization is obtained, but the average value before two combustion cycles may be obtained, or less than one combustion cycle, for example, between 2 and 3 TDC. An average value may be obtained.

Although the air-fuel ratio is actually shown as an equivalent ratio in the first embodiment and the like, it goes without saying that the air-fuel ratio and the equivalent ratio may be determined separately. Further, the feedback correction terms KSTR, #nKLAF, and KLAF are determined as multiplication terms, but may be addition terms.

In the above embodiment, the STR has been described as an example of the adaptive controller.
CS (model reference adaptive control) may be used.

In the above-described embodiment, the output of the single air-fuel ratio sensor provided in the exhaust system collecting portion is used. However, the present invention is not limited to this, and the air-fuel ratio sensor is provided for each cylinder. The air-fuel ratio feedback control may be performed for each cylinder based on the detected air-fuel ratio.

[0108]

According to the present invention, the load on the on-board computer can be reduced by reducing the amount of matrix operation.
As a result, an ordinary in-vehicle computer can complete the operation within 1 TDC.

According to the second aspect, even when the adaptive control parameter adjusting mechanism is performed in synchronization with a cycle longer than the predetermined crank angle, for example, a combustion cycle, the influence of the exhaust gas air-fuel ratio of the specific cylinder is strongly affected. I will not receive it.

[0110] Claim 3 has the same functions and effects as those of claim 2.

According to a fourth aspect of the present invention, also when the adaptive controller and the adaptive control parameter adjusting mechanism operate so that the actual fuel injection amount matches the target fuel injection amount, the present invention is also described in the first aspect. Similarly, the amount of calculation can be reduced, changes in the operating state can be dealt with as much as possible, and the specific cylinder is not affected.

[Brief description of the drawings]

FIG. 1 is a schematic diagram generally showing a fuel injection amount control device for an internal combustion engine according to the present invention.

FIG. 2 is a block diagram showing a configuration of a control unit in the apparatus of FIG. 1 in detail.

FIG. 3 is a main flowchart showing the operation of the fuel injection amount control device for an internal combustion engine according to the present invention.

FIG. 4 is a block diagram functionally showing the operation of the flow chart of FIG. 3;

5 is a block diagram similar to FIG. 4, showing the operation of the flowchart of FIG. 3 functionally centering on an STR controller and an adaptive control parameter adjustment mechanism;

FIG. 6 is a subroutine flowchart of the flowchart of FIG. 3;

FIG. 7 is a timing chart showing the operation of the flow chart of FIG. 3;

FIG. 8 is a subroutine flowchart of FIG. 3 similar to FIG. 6, showing the operation of the apparatus according to the second embodiment of the present invention.

FIG. 9 is a timing chart showing the operation of the flow chart of FIG. 8;

FIG. 10 is a block diagram similar to FIG. 4, showing the operation of the device according to the third embodiment of the present invention.

FIG. 11 shows the operation of the device according to the third embodiment;
FIG. 7 is a subroutine flowchart of the flowchart of FIG. 3 similar to FIG. 6.

FIG. 12 is a timing chart showing the operation of the flow chart of FIG. 11;

FIG. 13 is a main flow chart similar to FIG. 3, showing the operation of the device according to the fourth embodiment of the present invention.

FIG. 14 is a block diagram functionally showing the operation of the device according to the fourth embodiment.

FIG. 15 is a main flow chart similar to FIG. 3, showing the operation of the device according to the fourth embodiment of the present invention.

FIG. 16 is a block diagram functionally showing the operation of the flow chart of FIG. 15;

FIG. 17 is a timing chart illustrating a dead time in a fuel injection amount calculation of the internal combustion engine.

FIG. 18 is a timing chart illustrating the operation of the adaptive control proposed earlier by the present applicant.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Internal combustion engine 16 Throttle valve 20 Intake manifold 22 Injector 24 Exhaust manifold 36 Throttle opening sensor 38 Intake pressure sensor 46 Wide area air-fuel ratio sensor 50 Control unit

Continuation of the front page (72) Inventor Shusuke Akasaki 1-4-1 Chuo, Wako-shi, Saitama Prefecture Honda Technical Research Institute Co., Ltd. (56) References JP-A-6-17680 (JP, A) JP-A-6-17681 (JP, A) JP-A-6-42385 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) F02D 45/00 370 F02D 45/00 358 F02D 41/14 330

Claims (4)

(57) [Claims] 1. A fuel injection amount control means for controlling a fuel injection amount of a multi-cylinder internal combustion engine, an adaptive controller for adaptively matching the fuel injection amount to a target value, and an adaptive control parameter of the adaptive controller. A fuel injection amount control device for a multi-cylinder internal combustion engine having an adaptive control parameter adjusting mechanism for adjusting the fuel injection amount, wherein the fuel injection amount control means is operated in synchronization with a fuel control cycle for each cylinder at a predetermined crank angle, and the fuel system dead time of the controlled object from the adaptive controller
The control cycle is regarded as a value synchronized with a combustion cycle which is n times (n: an integer of 2 or more), and an input to the adaptive control parameter adjustment mechanism is performed in synchronization with the combustion cycle . The adaptive parameter based on the input
Fuel injection control apparatus for an engine, characterized in that the adjusting mechanism is configured to so that to adjust the adaptive parameters. 2. An input to the adaptive control parameter adjusting mechanism is performed by obtaining an average value of a control amount for each of the fuel control cycle or the combustion cycle, and the adaptive control parameter adjusting mechanism is configured to calculate the average value of the average. 2. The adaptive control parameter is adjusted based on a value.
A fuel injection amount control device for an internal combustion engine according to claim 1. 3. An input to the adaptive control parameter adjustment mechanism is performed by obtaining an average value of the adaptive control parameter for each of the fuel control cycle or the combustion cycle, and the adaptive control parameter adjustment mechanism is configured to output the average value. The fuel injection amount control device for an internal combustion engine according to claim 1, wherein the adaptive control parameter is adjusted based on an average value. 4. The fuel injection amount control device for an internal combustion engine according to claim 1, wherein the target value is at least one of a fuel injection amount, an equivalence ratio, and an air-fuel ratio.